Cast Iron Drain Pipe: Should it stay or should it go?

Was sent your way via the JB forum. I'm redoing a shower and underlying plumbing issues have sent me here for advice from you guys.

The house: 1971 build in Miami, FL on slab on grade.

The issue. I have a 2" CI drain from a walk-in shower stall that was cracked. I have removed the riser pipe and p-trap that was cracked with the idea to replace with PVC fernco'd to the CI horizontal drain. Now I am looking at a cast iron horizontal pipe that I am debating whether to replace with PVC or not.

Below is what the pipe looks like after flushing out the gunk with a garden hose. Which by the way it swallowed up every drop without any back ups for several minutes. So flow is seemingly not an issue.

So the big question is, would you replace this pipe at the cost of busting up 5 lineal feet of concrete back to the toilet? I do plan on staying in this house long term, possibly for the rest of my life. But I'd love to not have to take on this type of repair at this point. What say you, fellas? Should it stay or should it go? Does it look that bad? It's been in the ground for over 40 years.

Thanks, all!

Attached Files:

I should also mention this is a garage bathroom (or gardener's bathroom) in a house with 2 other bathrooms. This unit is not slated for daily use. Original design was for cleaning up after heavy garage or especially dirty outdoor activities. So nothing too heavy here; just occasional emergency usage if the other bathrooms are occupied.

My concern is that when you get to the connection you might find that he other line looks very similar on the inside. Where will the job stop? Structurally this pipe could work for a good number of years.

I don't think there is a right or wrong here, you might end up redoing it in 10 years, but if you hold to the the same standard, you might find that all of your old lines could use the same improvement.

Yes, the point of where one should stop is what is plaguing me on this one. Over at JB they are of the opinion that I should at least work my way out of the shower so I don't have to rip it up in the future. I can see the merit in that. Tearing out a bathroom floor just short of the shower is much better than having to rip up all the way to the shower drain. Especially if I plan to Kerdi this thing.

My one new worry here is that I can grab the 6" of pipe that are sticking out of the side of the hole I dug and I can move the pipe up and down a good 1/4". Is that normal? Seems to me if you can move a buried pipe it's broken close by. Maybe it's different for underslab pipes?

I got my hands on a cheap drain cam yesterday and will scope out the pipe today after hours and report back.

Terry, thanks for the warm welcome. Honor to have the man himself pop in on my first post. You won't get rid of me that easily tho. I'll be here for quite a while.

CI joints are solid...you should not be able to move things at all. Something underneath is broken, so keep going until you find solid pipe. Depending on the soil, a leak there may not show up, but draining underneath the slab is not a good solution!

Okay fellas got a cheap drain cam in there and spotted what seems to be a flexible fernco fitting that is flexing a bit about 16" in from the pipe opening. See below.

[video=youtube_share;lNolgiapQC4]http://youtu.be/lNolgiapQC4[/video]

Is my assumption correct? Just a fernco doing it's thing here? The flex is rubbery in nature and always springs right back into place. The p-trap I removed was connected with a fernco as well.

If I dug to this point and replace with PVC back up to the shower drain I will have effectively made it out of the shower and replaced it all with PVC. Mission accomplished. I don't see any reason to go any further than this because the entire house is in the same condition (and draining just fine to boot).

As a bonus, I have another video, which shows the entire shower branch to the main stack, a pause, a toilet flush (1:09) and then returning back out thru the pipe in reverse.